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real-time prediction of projectile penetration to laminates by training machine learning models with finite element solver as the trainer

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Defence Technology（防务技术） 2021年第1期17卷 147-160页

作者： Pushkar Wadagbalkar g.r.liu Department of Aerospace Engineering and Engineering Mechanics University of CincinnatiCincinnatiOH 45219USA

Studies on ballistic penetration to laminates is complicated,but important for design effective protection of *** means of study is expensive and can often be *** simulation has been an excellent supplement,but the computation is *** aim of this thesis was to develop and test an effective tool for real-time prediction of projectile penetrations to laminates by training a neural network and a decision tree regression model.A large number of finite element models were developed;the residual velocities of projectiles from finite element simulations were used as the target data and processed to produce sufficient number of training *** focused on steel 4340tpolyurea laminates with various *** different 3D shapes of the projectiles were modeled and used in the *** trained neural network and decision tree model was tested using independently generated test samples using finite element *** predicted projectile velocity values using the trained machine learning models are then compared with the finite element simulation to verify the effectiveness of the ***,both models were trained using a published experimental data of projectile impacts to predict residual velocity of projectiles for the unseen *** of both the models was evaluated and *** trained with Finite element simulation data samples were found capable to give more accurate predication,compared to the models trained with experimental data,because finite element modeling can generate much larger training set,and thus finite element solvers can serve as an excellent *** study also showed that neural network model performs better with small experimental dataset compared to decision tree regression model.

关键词： Finite element simulations Machine learning Neural networks Impact analysis Protective laminates Projectile Decision tree

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Meshless Methods Coupled with Other Numerical Methods

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Tsinghua Science and Technology 2005年第1期10卷 8-15页

作者： Y.T.gU g.r.liu CentreforAdvancedComputationsinEngineeringScience(ACES) DepartmentofMechanicalEngineeringNationalUniversityofSingapore10KentRidgeCrescentSingapore119260Singapore

Meshless or mesh-free (or shorten as MFree) methods have been proposed and achieved remarkable progress over the past few years. The idea of combining MFree methods with other existing numerical techniques such as the finite element method (FEM) and the boundary element method (BEM), is naturally of great interest in many practical applications. However, the shape functions used in some MFree methods do not have the Kronecker delta function property. In order to satisfy the combined conditions of displacement compatibility, two numerical techniques, using the hybrid displacement shape function and the modified variational form, are developed and discussed in this paper. In the first technique, the original MFree shape functions are modified to the hybrid forms that possess the Kronecker delta function property. In the second technique, the displacement compatibility is satisfied via a modified variational form based on the Lagrange multiplier method. Formulations of several coupled methods are presented. Numerical exam- ples are presented to demonstrate the effectiveness of the present coupling methods.

关键词： meshless method mesh-free method finite element method boundary element method coupling method stress analysis

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A node-based smoothed point interpolation method for dynamic analysis of rotating flexible beams

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Acta Mechanica Sinica 2018年第2期34卷 409-420页

作者： C.F.Du D.g.Zhang L.Li g.r.liu College of Civil Science and Engineering Yangzhou University School of Sciences Nanjing University of Science and Technology School of Aerospace Systems University of Cincinnati

We proposed a mesh-free method, the called node-based smoothed point interpolation method(NS-PIM),for dynamic analysis of rotating beams. A gradient smoothing technique is used, and the requirements on the consistence of the displacement functions are further weakened. In static problems, the beams with three types of boundary conditions are analyzed, and the results are compared with the exact solution, which shows the effectiveness of this method and can provide an upper bound solution for the *** means that the NS-PIM makes the system soften. The NS-PIM is then further extended for solving a rigid-flexible coupled system dynamics problem, considering a rotating flexible cantilever beam. In this case, the rotating flexible cantilever beam considers not only the transverse deformations,but also the longitudinal deformations. The rigid-flexible coupled dynamic equations of the system are derived via employing Lagrange’s equations of the second type. Simulation results of the NS-PIM are compared with those obtained using finite element method(FEM) and assumed mode method. It is found that compared with FEM, the NS-PIM has anti-ill solving ability under the same calculation conditions.

关键词： Meshfree method NS-PIM rigid-flexible coupled system dynamics rotating beams Dynamic response

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Smoothed finite element methods for effective simulation of bio-systems:soft,fluidic,and interactive

Smoothed finite element methods for effective simulation of ...

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第十一届全国生物力学学术会议暨第十三届全国生物流变学学...

作者： g.r.liu Chen Jiang Xu Han M.Li Taiyuan University of Technology Department of Aerospace Engineering Mechanics University of Cincinnati State Key Laboratory of Advanced Technology of Design and Manufacturing for Vehicle Body Hunan University College of Mathematics Taiyuan University of Technology

The simulation of bio-systems is one of the most challenging and important research topics,because it relates to the health of leaving *** is also a rapid developing multidiscipiinary area which involves engineering,biology,medicine science,computer science and *** new insights of behaviors of these muitiscale and multiphysical bio-systems are revealed from the quantitative analyses made by simulations in mo-

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Nanozyme catalysis in a crowded environment:The impact of diffusion and surface shielding

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Nano research 2024年第7期17卷 5795-5800页

作者： Vasily g.Panferov Juewen liu Department of Chemistry Waterloo Institute for NanotechnologyWaterlooOntario N2L 3G1Canada

Nanozymes are widely used in various applications as nanosized catalysts for replacing *** accurate estimation of the catalytic activity of nanozymes in real conditions is *** this article,for the first time,we systematically studied the effect of macromolecular molecules co-existing in the real system on the oxidoreductase(peroxidase,oxidase,and catalase)-mimicking nanozymes made of a gold nanoparticle core and a platinum shell,Prussian Blue,Mn2O3 and CoO *** were made with horseradish *** distinguished two main mechanisms of the negative impact of macromolecules on nanozyme catalysis—slowed diffusion and surface shielding of *** the first mechanism is typical for enzymes,the second one is specific only for *** the mechanisms is essential for developing approaches to reduce the unavoidable impact of macromolecules for various analytical and biomedical applications.

关键词： molecular crowding biosensors nanoparticles

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Control system design for a pressure-tube-type supercritical water-cooled nuclear reactor via a higher order sliding mode method

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Nuclear Science and Techniques 2024年第1期35卷 145-154页

作者： M.Hajipour g.r.Ansarifar Department of Nuclear Engineering Faculty of PhysicsUniversity of IsfahanIsfahan 81746-73441Iran

Nuclear power plants exhibit non-linear and time-variable ***,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWr)is a fourth-generation conceptual *** an SCWr,the non-linear dynamics of the reactor require a controller capable of control-ling the *** this study,a pressure-tube-type SCWr was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled *** an SCWr,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power *** point kinetics equations with three groups of delayed neutrons were used in the ***-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous *** controlled parameters were reactor power,steam temperature,and ***,for these parameters,the PI controller had certain instabilities in the presence of *** classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering *** was highly accurate and stable and had a small computational *** reality,it followed the desired values without oscillations and chattering.

关键词： Supercritical water nuclear reactor Higher order sliding mode controller Steam temperature Steam pressure Point kinetics model

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Superior comprehensive properties of LaFe_(11.8)Si_(1.2)/Ce_(60)Co_(40) magnetocaloric composites

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Journal of rare Earths 2024年第6期42卷 1073-1086,I0003页

作者： Xichun Zhong Yuanxin Li Yucai Wu Jiaohong Huang Cuilan liu Jian liu Zhongwu liu Minglong Zhong Zhenchen Zhong r.V.ramanujan School of Materials Science and Engineering South China University of TechnologyGuangzhou510640China Baotou research Institute of rare Earths Baotou014030China Center for Advanced Solidification Technology School of Materials Science and EngineeringShanghai UniversityShanghai200444China Jiangxi KeyLaboratory for rare Earth Magnetic Materials and Devices&Institute for rare Earth Magnetic Materials and Devices(IrEMMD) Jiangxi University of Science and TechnologyGanzhou341000China School of Materials Science and Engineering Nanyang Technological University639798Singapore Singapore-HUJ Alliance for research and Enterprise(SHArE) The Smart Grippers for Soft Robotics(SGSR)ProgrammeCampus for Research Excellence and Technological Enterprise(CREATE)138602Singapor

LaFe_(11.8)Si_(1.2)/10 wt%Ce_(60)Co_(40) composites were prepared by spark plasma sintering and subsequent diffusion annealing.A novel core-shell structure is observed with the LaFe11.8Si1.2 particles as the core and the(La,Ce)_(2)(Fe,Co,Si)_(17)(2:17)phase as the *** diffusion annealing time(t_(a))increases,this core-shell structure is replaced by the formation of the(La,Ce)_(1)(Fe,Co,Si)_(13) *** at 1323 K for 12 h results in samples with(-ΔSM)^(max) of 9.30 J/(kg·K)(Δμ0H=2 T),good mechanical properties((σbc)^(max)=402 MPa,ε=4.21%)and thermal conductivity of 8.7 W/(m·K).Thus,bulk composites with excellent comprehensive properties for magnetic refrigeration are obtained in this work.

关键词： LaFe_(11.8)Si_(1.2)/Ce_(60)Co_(40)composites Spark plasma sintering Diffusion annealing Microstructure evolution Magnetocaloric effect rareearths

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Doubled haploid technology and synthetic apomixis:recent advances and applications in future crop breeding

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Molecular Plant 2024年第7期17卷 1005-1018页

作者： Yanzhi Qu Alisdair r.Fernie Jie liu Jianbing Yan National Key Laboratory of Crop genetic Improvement Huazhong Agricultural UniversityWuhan 430070China Hubei Hongshan Laboratory Wuhan 430070China Department of Molecular Physiology Max-Planck-Institute of Molecular Plant Physiology14476 Potsdam-GolmGermany Center of Plant Systems Biology and Biotechnology 4000 PlovdivBulgaria azhouwan National Laboratory Sanya 572024China

Doubled haploid(DH)technology and synthetic apomixis approaches can considerably shorten breeding cycles and enhance breeding *** with traditional breeding methods,DH technology offers the advantage of rapidly generating inbred lines,while synthetic apomixis can effectively fix hybrid *** this review,we focus on(i)recent advances in identifying and characterizing genes responsible for haploid induction(Hl),(ii)the molecular mechanisms of Hl,(ili)spontaneous haploid genome doubling,and(iv)crop synthetic *** also discuss the challenges and potential solutions for future crop breeding programs utilizing DH technology and synthetic ***,we provide our perspectives about how to integrate DH and synthetic apomixis for precision breeding and de novo domestication.

关键词： maize doubled haploid technology haploid induction synthetic apomixis precision breeding

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Plant gene co-expression defines the biosynthetic pathway of neuroactive alkaloids

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Molecular Plant 2024年第3期17卷 372-374页

作者： Fang liu' Alisdair r.Fernie Youjun Zhang Key Laboratory of Seed Innovation Institute of Genetics and Developmental BiologyChinese Academy of Sciences100101 BeijingChina Max Planck Institute of Molecular Plant Physiology Am Muhlenberg 114476 Potsdam-GolmGermany Center for Plant Systems Biology and Biotechnology 4000 PlovdivBulgaria University of Chinese Academy of Sciences 100049 BeijingChina

Transcriptomes comprise gene co-expression clustersor modules,showcasing distinct patterns of coordinated expression among groups of genes across independent biological samples(Serin et al.,2016).The"guilt-by-association"hypothesis suggests the functional importance of these clusters;for example,co-expressed genes associated with metabolism typically contain genes encoding several enzymes associated with the same pathways.

关键词： metabolism alkaloids

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Frequency regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC ***,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC ***,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is ***,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind *** simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed

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